1. Field of the Invention
The present invention relates to a program constructing technology, and more particularly relates to a technology to dynamically construct a plurality of programs similar to each other.
2. Description of the Related Art
A Web browser program including a Web server program and a Web client program is utilized in wide areas including application systems such as information searching and online shopping on the Internet. In such systems, data is transmitted or received between a Web server and a Web client by following an HTTP protocol. Data transmitted from a Web server to a Web client is called an HTML document following a fixed specification. There are two major methods of transmitting an HTML document. One of the methods is a static HTML document transmission, whereas the other method is called a dynamic HTML document transmission. In the static HTML document transmission method, the HTML document is created and stored in a file at the Web server, in advance. The Web server transmits the HTML document to the Web client if the Web client specifies the HTML document and requests the Web server to transmit the HTML document by using a URL.
On the other hand, in the dynamic HTML document transmission method, the Web server program, by following a CGI (Common Gateway Interface), calls one of other CGI programs. A CGI program called by the Web server program outputs data following a specification of the HTML document. Subsequently, the Web server program transmits the data to the Web client.
By use of a dynamic HTML document construction method, an HTML document can include personal information such as a user name and a user ID. As a result, such personal information can be displayed on a Web client's monitor. The personal information can be included in the HTML document by one of the dynamic HTML document construction methods inserting a programming language to a variable part of an original HTML document. An advantage of such method is that perception of contents of a modified HTML document is uncomplicated since a program is inserted to the original HTML document. According to the method of inserting the programming language to the original HTML document, an HTML document displaying information stored in a database as a table can be created, by taking the steps of preparing an original HTML document, and by replacing or inserting letters on the original HTML document.
The above-described dynamic HTML document construction method is effective in a case of performing simple operations including replacement of letters and addition of a row to a table. However, in a case in which the above-described dynamic HTML document construction method is applied to replacement of contents obtained by a complicated calculation, the original HTML document becomes more complicated and less understandable. The simple replacement of letter in an HTML document cannot support construction of the HTML document utilized in a complicated Web-base application. For instance, a plurality of HTML documents occasionally include an identical main part, but partially include input items different from each other. This difference is neither a simple word-line difference, nor simple addition of a row to a table. For example, an application system is considered, the application system checking a qualification of a user logging on to the application system, and displaying an input field and a button corresponding to a user rank in a company on a next screen. In the application system, there are variations of the next screen to be displayed according to the user rank such as a regular staff or an executive. The variations can be hardly covered by the above-described method.